CHEM 222 Chapter Notes - Chapter 14: Benzene, Chlorobenzene, Substituent
20 Jan 2017
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Benzene substitution: benzene only reacts with bromine in the presence of a lewis acid catalyst such as. Febr3 --leads to substitution (not addition: only one monobromobenzene or monochlorobenzene formed, bc only one of 6 h atoms active towards these agents, and hs are all equivalent. The annulenes: annulene: class name for monocyclic compounds --structures of alternating single and double bonds, ring size indicated by number in brackets; [6]annulene is benzene, are aromatic if molecules have 4n+2 pi electrons and planar carbon skeleton. Aromatic ions: some charged monocyclic rings can also be aromatic compounds i. e. cyclopentadienyl or cycloheptatrienyl. If there is an sp3 carbon on ring, electrons cannot be delocalized over the entire ring and therefore isn"t aromatic --no available p orbital: but ok if + charge, brings it to sp2. Aromatic, antiaromatic, nonaromatic: aromatic: pi electrons delocalized over the entire ring and compound stabilized by pi-electron delocalization (resonance energy, compare ring to open-chair compound with same number of pi electrons.
